Midwest (Missouri) and this will be an ICF home. The window will face North backed up by a lake and a covered patio.

If you are thinking of a 60x60 sliding window, might as well go for the extra 20 inches at the floor and have a sliding door instead. I like pass through windows, but the size there is almost the size of a full door.

When I first saw these I was intrigued. They remind me of the old drive-in restaurant walk up counters. I'm skeptical that these aren't just a fleeting trend.

I have deck seating right below my sliding kitchen sink window and not once have I ever wished for the ability to pass something between myself and someone seated there--there's a door about 8 feet away.

I think my kitchen window is 4-0 x 3-0 and slides with ease. 5-0 x 5-0--if you're reaching over a counter--sounds like it could require a bit more effort to open/close. And if something isn't easy, we humans will tend to adapt and just use the door.

A 48x36 window would be far more reasonable. At 60x60 the window would hit the counter and the ceiling if they are 8 foot tall. And sort of awkward for the sliding to work since the majority of the window extends above where comfortable handle placement would be. Pass through windows can be really handy. But only if they are pratical to use.

What are you expecting to pass through the window? I have found a door works very well as a pass thru window.

Sliders have the obvious issues of a tract that gets dirty, a large frame running down the middle of the window, and no easy way to screen for bugs or cover for privacy/light (does not seem like an issue here).

They also leak more air than other types of window. They tend to be used in warmer climates. If they leak more air, I suppose it is easier for ants to get through - not what you would want in a kitchen.

The above window takes away the framing, sealing and tract concerns. I wonder how they open and close it? I imagine the strut opens it - but like a car's strut can wear out. Then they use a rod to close it?

My thought on the pass through is sort of like what the above posters have said. It sounds cool and all but not very practical. It takes 2 people to make it work - every single time. You would not do it with heavy or hot things. Unless you envision a bartender type of person standing at the kitchen sink during social events, I don't see the value. A well placed door seems way more practical. Maybe an outdoor kitchen of some type.